1. Field
The exemplary embodiments disclosed herein relate to a semiconductor device, and more particularly, to a semiconductor device including a two-dimensional (2D) material.
2. Description of Related Art
A two-dimensional (2D) material is a single-layered solid of atoms having a predetermined crystal structure, and graphene is a representative 2D material. Graphene has a monoatomic layer structure in which carbon atoms form a hexagonal structure. Graphene may have a symmetrical band structure on the basis of a Dirac point, and since an effective mass of electric charges at the Dirac point is very small, the graphene may have a charge mobility at least ten times (significantly thousands times or more) greater than that of silicon (Si). Further, graphene may have a very large Fermi velocity. Such graphene has entered the spotlight as a next-generation material that can overcome limitations of existing devices, and by starting research on such graphene, research and development on various 2D materials having insulating or semiconductor characteristics have been conducted.
A large number of semiconductor devices including 2D materials include P-N junctions formed by at least 2D material. There are several structures and/or methods for forming the P-N junction of the 2D material, and the following ways are representative thereof. The first method is a method of forming a P-N junction by partially inducing P-type region and N-type region in a 2D material layer through an electrical gating in a state in which a double gating structure is formed on a back surface of a substrate, on which the 2D material layer is formed. The second method, which is a method using chemical doping, is a method of forming a P-N junction by inducing a P-type or N-type material in a portion of a 2D material layer. In this case, an N-type or P-type material may be induced in the other portions of the 2D material layer if necessary. The third method is a method of forming a P-N junction by bonding a P-type material to an N-type material, and both sides may be 2D materials, or one side may be a bulk material and the other may be a 2D material.
However, such a P-N junction using an existing 2D material has a complex structure in which two different voltages should be applied, is difficult to ensure controllability or reproducibility thereof, or uses different types of materials as a P-type material and an N-type material, and thus an interface issue may be caused.